Field of the Invention
The present invention relates to an image reading apparatus which reads an image of a document according to a read request from an external device.
Description of the Related Art
An image reading apparatus has been known which reads an image of a document according to a read request from an external device, generates image data corresponding to the image, and transmits the image data to the external device. A function by which the image reading apparatus reads an image of a document according to a read request from an external device will hereinafter be referred to as a pullscan function.
Conventionally, if the image reading apparatus executes a pullscan function, the user needs to manually set the image reading apparatus to a pullscan mode. It has been necessary that the user manually sets the pullscan mode each time the pullscan function is executed. Hence, an image reading apparatus that automatically enters a pullscan mode and can read an image of a document according to a read request from an external apparatus has been discussed.
Recent image reading apparatuses typically enters a power saving state to reduce power consumption during standby time. A conventional image reading apparatus which is manually set to the pullscan mode does not enter the power saving state if the image reading apparatus is set to the pullscan mode by the user. Thus, there has not been a need to take account of receiving the read request from the external device in the power saving state.
An image reading apparatus that automatically enters the pullscan mode according to a read request from an external device may receive a read request when in the power saving state. In such a case, the image reading apparatus needs to automatically recover from the power saving state. According to Japanese Patent Application Laid-Open No. 2014-230070, if an image reading apparatus receives a read request in a power saving state from an external device, the image reading apparatus recovers from the power saving state and becomes able to read a document.
The image reading apparatus discussed in Japanese Patent Application Laid-Open No. 2014-230070 recovers from the power saving state if a read request for an image of a document is received. Therefore, the external device cannot figure out a state of the document to be read before transmitting the read request. The image reading apparatus discussed in Japanese Patent Application Laid-Open No. 2014-230070 can thus recover from the power saving state and start a read operation according to the read request although there is no document placed on an automatic document conveyance apparatus (hereinafter, referred to as an automatic document feeder (ADF)) which conveys a plurality of sheets to a reading unit one by one.